Internal combustion engine



June K. J. E. HESSELMAN ET AL 2,046,264

INTERNAL COMBUS T ION ENGINE 2 Sheets-Shet 1 Original Filed Oct. 6, 1954 l x l ll Illlllllllll I' /v N 4: 6 4, v .w a, 2 w

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J 1936. K. J. E. HESSELMAN ET AL 2,046,264

INTERNAL COMBUS T ION ENGINE Original Filed Oct. 6, 1954 2 Sheets-Sheet 2 A? 4:2 a 52 Je z i g 6' C JO 3,, I i

I E I I 4.1- l /g f I i i f l -/0 Fatented June 3Q, 3936 yric v amazes manner. conmnsrron enema Knot Jonas miss Hessehnan, Saltsio-Storangen, and Torbjiirn Viktor Dillstriim, Stockholm,

Sweden, assignors to poration Ltd, London oi Great Britain Hesselman Motor Cor- England, a corporation 7 @rlginal application October 6, 1934, Serial No.

this application Decembar 21, 1935, Serial No. 55,572. In Sweden idarchlii. 193d This application is a division of our co-pendinggggplication Serial No. 747,134 filed October 6, 1

The present invention relates to internal combustion engines, of the type in which finely divided on atomized liquid fuel is injected into the combustion chamber of the engine and mixed with air therein to form a combustible fuel charge. More particularly the invention relates to engines of the type in which, during normal operation, a complete or substantially complete charge is formed in the engine cylinder prior to the time of ignition and is ignited, in normal operation of the engine, by spark or a like kind of ignition. Stated in another way, the invention relates to engines operating substantially in accordance with the so-called Otto cycle, rather than in accordance with the Diesel cycle which contemplates injection of fuel into'an charge which has been compressed to such high'pressure that the resulting temperature of the air causes ignition oi the fuel due to the heat oi compression upon contact of fuel with the compressed air charge. Still more particularly the invention relates to engines of the above described Otto cycle type adapted to operate at relatively high speeds.

In one of its aspects, the present invention may be considered as an improvement, with re-' spect to certain kinds of engines, upon the construction of engines of the Hesselman type as disclosed in U.'S. Patent No. 1,835,490.

Amongst the principal objects of the invention are; to provide an improved construction resulting in improved efilciency of operation and better fuel economy in engines of the kind under con sideration; to provide an improved engine constructlon whereby engines of the End under consideration may be operated at high speed with 40 high efliciency; to provide improved engine construction for engines of the character under consideration which permits the satisfactory em ployment of higher compression ratios than it has been possible to employ heretofore, with consequent increase in power output for a given size of engine, and to provide improved apparatus whereby ordinary gasoline engines may be converted easily and cheaply for operation as injection engines using relatively heavy and non- 50 volatile oil for fuel. I

Other and more detailed objects of the invention, together with the manner in which the several objects are attained and the advantages to be derived from the use of the invention, will 5 appeanmore fully in conjunction with the en-- suing description of several embodiments of apparatus for carrying the invention into efiect, which embodiments are illustrated in the accompanying drawings forming a part of this specification. g I

In the drawings: Fig. 1 is a longitudinal section through the cylinder of an engine embodying the invention; Fig. 2 is a view takenon the line 22 of Fig. 1; Fig. 3 is a section similar to Fig. 1 showing another application of the invention;

Fig. 4 is a view taken on the line 45 of Fig. 3; Fig. 5 is a section showing still another application of the invention; and

Fig. 6 is a view taken on the line t-tof Fig. 5. Referring now more particularly to Figs. 1 and 2, the engine illustrated is of the overhead valve type and comprises the cylinder block it having the separable inserted cylinder liner l2 and the cylinder head Hi. Head It is detachable from v2 the cylinder and is retained in place by the usual cylinder head studs (not shown). Piston it is provided with a head or crown portion it from. which extends upwardly the peripheral collar portion 20, the construction providing what may be termed a cup at the upper end of the piston. The piston is connected to the usual connecting rod 22 by means of the wrist pin 26. The piston is provided with the usual compression and oil control piston rings 26, 28 and for reasons which will hereinafter appear one or more of these rings is advantageously seated in the collar portion of the piston. as shown in Fig. 1. In the embodiment illustrated, the cylinder head it has a generally flat under surface forming the top wall of the combustion or c pression chamber 30, the wall surface oi which is substantially entirgly defined by the under side of the head and th cup portion of the piston when the piston is at the upper end of its stroke. Whenthe piston is at top dead center position, the top of the collar portion of the piston preferably extends to, or almost to, the top edge of the cylinder wall so as to substantially cover the lubricated side wall surface of the cylinder. Head it carries the inlet valve 32 and exhaust valve 36 which valves are closed in the usual manner by springs 36 and are opened downwardly toward the combustion chamber by rocker arms 33 actuated by push rods it, the rods it in turn being actuated by cams on the usual cam shaft (not shown).

Air is admitted to the combustion chamber by way 01 inlet valve 32 through the inlet passage 42 formed in the head and adapted to be con- Cal . The exhaust passage 50 leads from the ex-' haust valve 34 to the side of the cylinder head in the 'usual manner for connection to the exhaust manifold (not shown).

A spark plug 58 is mounted in the head l4 so as to project downwardly into the combustion chamber from the under side of the head II. In an engine of the kind illustrated in Fig. 1, that is, with relatively small bore, the plug is advantageously located near the periphery of the combustion chamber. Plug 58 is preferably 'of the usual high tension jump spark type to which current is supplied at timed intervals by the usual battery or magneto ignition system.

An injection nozzle 52 is mounted so that its tip 56 is located in the upper portion of the combustion chamber 30. Advantageously the injection nozzle is mounted in head l4 although it will be evident to those skilled in the art that the line of partition between the cylinder block and the head may be inclined so that the injection nozzle may be mounted in the block in a position corresponding to the position shown in Fig. 1. The tip of the injection nozzle is advantageously located, in an engine of the kind described, near the periphery of the combustion chamber at the side thereof opposite the spark p ug.

- cylinder bores to inject the fuel in two diverging jets which are projected transversely of the cylinder and downwardly from the nozzle at an angle to the axis of the cylinder. The center lines of the jets, when injection is as above described, are shown at 60 and 62.

Instead of jets of the kind illustrated, the charge may be injected inthe form of a fiat fan shaped jet of wide lateral dispersion directed angularly downwardly from the injection nozzle but, for practical operating reasons, we prefer to employ one or more jets projected from circular orifices which are less likely to clog than is a slit orifice, one dimension of which must be exceedingly small.

In order to prevent interference between the collar portion of the piston on the one hand and the spark plug, injection nozzle and valves on the other hand, the collar portion of thepiston, in small engines, may be recessed at 64,, 65 and 66 as indicated in Fig. 1. It will be observed, however, that even with such minor recesses, the collar portion of the piston is continuous for the greater part of its height above the bottom of thepiston cup and for the purposes of the present invention may be considered as continuous. With the above described construction in mind, we will now consider the more important requirements for best attaining the objects of the present invention and the manner in which the above described construction meets such requirements.

. In an engine of the character under consideration, the compression or combustion chamber is located substantially entirely within the engine cylinder and, with. such an arrangement, it is highly desirable when atomized and relatively '5 non-volatile liquid fuel is injected that none of the fuel reaches the cylinder wall. In this con nection, it is to be pointed out that with :an engine of the kind under consideration, a serious problem arises which is not present in engines 10 of comparable size operating on the Diesel cycle.

" As previously pointed out, in the kind of engine we are considering, fuel is injected and-the charge is formed prior to the time of ignition. When this is done, the fuel which is injected at the commencement cf the injection period is projected across the cylinder and during the period between the commencement of injection and the time of ignition, which time'is usually somewhat after the termination of the injection period, the cylinder contains a charge of atomized oil being mixed with the air to form the proper combustible charge for firing at the proper time.

During this period, it is highly important to prevent exposure of the lubricated cylinder wall sur- 25 face, or as much thereof as possible, to contact with the fuel charge. The cylinder walls are relatively cool, being ordinarily water jacketed or specially cooled by air or other media and contact of the fuel with cool and lubricated cylinder wall surface ca adherence of fuel to the cylinder wall surf ce with consequent loss of fuel for combustion purposes and also serious dilutio of the lubricating oil.

In the form of engine construction according to the present invention, the difiiculty of forming an atomized charge prior to ignition is overcome by protecting the cylinder wall with the collar portion of the piston as the latter approaches the end of the compression stroke and by directing the fuel charge substantially entirely into the cupped portion of the piston. In a typical engine of the kind under consideration, injection of fuel may commence in the neighborhood of 60 ahead of top dead center although inengines operating at 45 relatively low speeds injection may commence even'later in the cycle. With a piston of the kind described arranged so that the top of the collar portion of the piston extends substantially to the top of the combustion chamber at top dead center, only a relatively small portion of the cylinder side wall surface is exposed at the time injection commences. It takes an appreciable amount of time for the fuel first injected to travel across the cylinder and by the time this travel has taken place the continued upward movement 'of the piston places the collar portion in a position such that the cylinder wall is futher covered and protected from impingement there against of the injected -fuel. Stated in another way, the collar portion of the piston is in the zone of fuel injection at the time injection takes place during the latter part of thecompression stroke.

In order to secure the most satisfactory performance of engines of the character described, particularly at part load when the amount of fuel injected is relatively small, it is desirable to assist atomization by some degree of heating of the oil prior to ignition, even to the extent of partial vaporization thereof. The piston is at higher tem- 70 perature than the cylinder and, by injecting fuel into the cupped portion of the piston, the formation of a readily ignitible fuel charge is materially aided by the heat of the piston.

In operation, the air charge, which is-drawn into the cylinder through the inlet passage 42 during the suction stroke of the piston is, in the embodiment illustrated, given a rotary motion within the cylinder due to the tangential admission of the air along the ramp 48 at one side of the inlet valve 32,

and this rotary movement continues during the compression stroke of the engine.

In the preferred embodiment of the invention, we make use of means for imparting tangential admission of the air so as to secure a relatively high speed of whirling movement of the air in the cylinder during the suction and compression strokes for reasons which will hereinafter more fully appear but, as will further be explained, special means for providing tangential admission may not be essential to the operation of all engines within the scope of the invention.

In order to avoid fouling of the spark plug as well as to assist in forming a readily ignitible mixture prior to ignition, the main body of the fuel charge is preferably injected into the cylinder in a direction other than directly at the spark plug and, in the embodiment illustrated, this is accomplished by the downward and lateral projection of the jets as indicated by lines 60, 62. Naturally, there will be some dispersion of fuel from the center of any jet or jets projected into the chamber but such dispersion of the fuel is such that penetration of fuel particles from the outer portions of the jet or jets, whichmay be directly toward the plug, is insufficient to cause amounts of fuel suflicient to result in fouling, to strike the Plug.

In this connection, the downwardly projectingposition of the plug from the head into the combustion chamber is of materially practical importance since such unburned liquid fuel as may strike the plug and remain thereon will drain to the lower end of the plug and not collect in quantitles on the insulated portions of the plug where such collection would result in short circuiting of the plug and consequent failure of proper action. Moreover the exposed position of the projecting inner end of the plug leaves this portion in a position where it is swept by movement of the air charge within the cylinder during the suction and compression strokes, and such movement of the charge not only serves to assist in cooling the plug so as to keep it below a temperature causing preignition, but also apparently assists in keeping the plug free from accumulations of oil thereon.

As previously stated, we prefer to provide special means for insuring whirling movement of air in the cylinder during the suction and compression strokes, which movement will continue to the end of the compression stroke. Such movement we find to be advantageous when fuel is injected in the manner illustrated in Figs. 1 and 2 since the movement of the air in the general direction indicated by the arrows in Fig. 2 insures fuel from the jet projected along the line 62 being carried to the plug so that an ignitible mixture is in the vicinity of the plug at the time of ignition. Due to the upward movement of the piston during the injection period, which movement ordinarily continues beyond the time of ignition since ignition is usually ahead of top dead center, there is some upward movement of the air in the combustion chamber and this aids in bringing fuel from this downwardly directed jet to the vicinity of the electrodes at the time of ignition. The fuel injected along the line 60, which is projected in a direction generally against the movement of the air, tends to be deflected still further downwardly by the moving air.

While we have found that a regularly defined rotary motion of the air in the cylinder induced by special means for tangential admission is, in most instances, a very' desirable factor, there are other considerations which must be taken-into account in this connection with respect to different specific engine designs. As is well known, high volumetric efiiciency is highly desirable. That is, it is highly desirable to be able to introduce into a cylinder of given size as great a weight of air as possible in order to burn the maximum of fuel per charge and thus secure the maximum amount of power from a cylinder of given size. Extremely high rates of air rotation obtained by special tangential air admission means are ordin'arily accompanied by some loss in volumetric efficiency due to the resistance to flow or restricted area of inlet opening accompanying the useofsuch means. We have discovered thatwith an overhead valve engine of the kind illustrated, theoifset position of the inlet valve with respect to the axis of the cylinder, coupled with the usual form of air inlet passage, which extends laterally to one side of the valve, may produce lateral movement of the air in the cylinder as it is admitted thereto, in a manner such that a certain amount of what may be termed generally whirling movement of the air in the cylinder results. Such COD-,- struction gives the minimum in the way of resistance tending to reduce volumetric efliciency and,

in certain kinds of engines, it may be possible to.

When it is desired to make use of relatively high speed air rotation and tangential air admission means is employed in order to insure this character .of air rotation, the smoothly symmetrical form of chamber resulting from the use of the continuous collar piston is of assistance since there is with this form of chamber minimum loss in speed of air rotation between the entering speed and the speed existing at the end of the compression stroke. Consequently, in order to obtain a given speed of air rotation toward the end of the compression stroke, that is, during the injection period, minimum air speed above this given speed is required for the air entering the cylinder and the air admission means can therefore be constructed so as to produce the minimum pressure drop.

While the present construction permits the compression ratio to be increased as compared with the compression ratios heretofore found to be feasible, it is to be understood that the increased compression ratios that may be employed in accordance with the present invention are substantially lower than the compression ratios employed for Diesel engines, and that the engine is,

insofar as compression classification is concerned, to be considered as a low compression rather than a high compression engine. The range of compression ratios employed in engines of the kind with which the present invention is concerned is of an order such that the engines are not sub-' jected to the severe mechanical stresses characteristic of Diesel engines and such engines may therefore have substantially the same ratio 017 40 plug 58 located relative to each other as in the version of an existing gasoline engine requires weight per horsepower as gasoline engines constructed for the same character of service.

In an engine of the characterlunder discussion ignition is primarily effected bythe spark produced at the plug, butit is not intended that the invention be limitedto engines where ignition occurs at all times and under all conditions of operation by spark alone. In an engine such as that illustrated, the amount of heat generated under continued full load or overload operation conditions may produce ignition at the end of the compression stroke, but ignition of this character and under-such conditions is not productive of the same undesirable character of engine operationand therefore the conversion of such engines does not require alteration or rebuilding with respect to the major portion of the engine. With apparatus according to the present invention, the cononly replacement of the existing head and of the existing pistons, and insome instances of the existing inlet valves.

In Figs. 3 and .4 we have illustrated still another form' of head for carrying the invention into effect. In this embodiment the'head llc is generally the same as that illustrated in Fig. 1, and is provided with injection nozzle 52 and spark embodiment of Fig. 1. In the present embodiment, however, the inlet valve 32 is seated substantially in the .plane of the lower face of the head, and tangential admission of air to the compression chamber 30 is effected by means of anair inlet passa e 42a, which may be said to be' of generally Venturi form having a throat 42b and a longitudinal axis inclined with respect to the transverse plane of the cylinder and tangential with respect to the longitudinal axisof the cylinder. For some types of engines this specific form of air inlet may be preferable to others, and

it will be understood, of course, that this type of inlet may be combined with other specific features of constructionshown in other embodiments herein. v Figs. 5 and 6 illustrate a slightly different application of the invention. The cylinder head Md is in general of the same construction as that shown in Fig. 3, but in this instance the injection nozzle 52 and the spark plug 58 are located adjacent to each other on the same eter of the cylinder.

In all of the embodiments shown herein, injection of.fuel is timed so that a fog of finely atomized fuel is carried by the movement of the air in the cylinder to the vicinity. of the 'elec trodes of the plug when the spark occurs. Thereside of .the diamof injection with res'pect'to the timing of the spark may be somewhat different in the form of apparatus shown in Fig. 5'and in the forms shown in the remaining figures, but the manner in which the timing may be varied will be understood by the axis of the cylinder.

those skilled in the art and need not be described herein in detail for an understanding of the present invention.

It will be observed that all of the modifications hereinbefore described have certain features in common which" are generally characteristic of the invention. Of these we consider the following to be of major importance. In each case, the

combustion chamber is of generally circular form and is also generally symmetrical about the longitudinal axis of the cylinder. It may be said to be in the form of a body of revolution about We intend to include in the meaning of the above terms as herein employed combustion chambers which may be slightly irregular, as, for

example, in some of the forms ofcombustiori chamber construction shown in U. S. Patent No.

2,028,760 granted January 28, 1936 to T. V. D111- 1 strom, wherein the piston head is angularly disposed and wherein there is an irregular recess for the inlet valve in the cylinder head. The primary requirement is that the combustion chamber be of what we. may term the usual form of overhead valve engines, adapted to facilitate the substantially regular whirling or rotation of the air admitted to the cylinder.

In all of the modifica-.

tions the injection nozzle and plug are carried in the head and project into the main combustion space, preferably in positions where the active rotating air.

By'carrying the injection nozzle and plug in 'the head it is not only possible to make use of the struction would be impossible with the injection ends of these elements are in the path of the nozzle and plug, or either, carried in the cylinder;

side wall, -It willalso be evident that in each casethe plug, being carriedin the head, extends vertically downward oris inclined downwardly into the combustionchamber from a position generally above the combustion chamber. This positioning of the plug is advantageous in that it facilitates drainage from the plug of any unatomized oil that may adhere thereto due to injection into the cylinder of improperly atomized oil by a' partially clogged or otherwise defective -with numerous different specific forms of apparatus, and that its application is not confined to any one particular engine construction. The

invention is therefore to be considered as embrace ing all forms of apparatus falling within the scope of the appended claims when they are construed as, broadly as is consistent with the state of the prior art. fore, the timing of the commencement and ending .While in order to assist the reader in an understanding of the invention we have set forth certaintheoriesregarding the action which takes place in an engine structure embodying the invention,. whi ch theories are based upon observation of the performance of engineswhich we have 75 specific kinds of gasoline engines. to injection,

engines operating in accordance with the present invention, are claimed.

What we claim is:

1. A low compression internal combustion engine of the explosion type having liquid fuel in.- jection commencing substantially ahead of top dead center and spark ignition for igniting a combustible air-fuel mixture formed prior to ignition, including a cylinder, a cylinder head, a piston in said cylinder having a substantially continuous upwardly extending collar portion, said piston, toward the end of the compression stroke, providing with the under side of the head a generally circular main combustion chamber substantially symmetrical with respect to the axis of the cylinder and having. substantially minimum cylinder wall surface exposed and themajor portion of said chamber being disposed within'the piston, means for admitting air during the suction stroke in a manner creating whirling movement of the air about the axis of the cylinder during'the suction stroke, which whirling movement continues during the compression stroke, including a valve located above the piston and. opening toward the combustion chamber from the underside of said head, means for exhausting combustion gases including a valve located above the piston and opening toward the combustion chamber from the underside of said head, a spark plug projecting downwardly into said main combustion chamber and in a position exposed to the movement of the whirling air. across the inner end of the plug during the suction and compression strokes, and

fuel injection means for projecting finely divided liquid fuel duringthe latter portion of the compression stroke transversely of the cylinder into the portion of the combustion space formed by the piston so that a substantial portion of said continuous upwardly extending collar portion,

movement continues during the compression,

stroke, including a valvel'ocated above the piston and opening toward the combustion chamber from the underside of said head,'means for exhausting combustion gases including a valve lo.-

cated above the piston and opening toward the combustion chan'iberfron'i the underside of said head, a spark plug projecting downwardly into said main combustion chamber and in aposition exposed to the movement of the whirling air across the inner end of the plug during the suction and compression strokes, and fuel injection means for projecting a plurality of jets of finely divided liquid fuel during the latter'portion of the compression stroke transversely of the cylinder and. in obliquely downward direction into the portion of the combustion space formed by the piston so that a substantial portion of said combustible fuel air mixture is formed in said portion of the combustion space below the level of the inner end of the plug. g

3. A low compression internal combustion engine of the explosion type having liquid fuel injection commencing substantially ahead of top dead center and spark ignition for igniting a combustible air-fuel mixture formed prior to ignition, including a cylinder, a cylinder head, a piston in said cylinder having a substantially continuous upwardly extending collar portion,

, said piston, toward the end of the compression strokalproviding with the under side of the head a generally circular main combustion chamber substantially symmetrical with respect to the axis of the cylinder and having substantially minimum cylinder wall surface exposed and the ,major portion of .said' chamber being disposed within the piston, means for admitting air during the suction stroke in a manner creating whirling movement of the air about the axis of the cylinder during the suction stroke, which whirling movement continues during the compression stroke, including a valve located above, the piston and opening toward the combustion chamber hausting combustion gases including a valve located above the piston and opening toward the combustion chamber from the underside of said.

head, a spark plug located in said head and projecting downwardly into said main combusfrom the underside of said head, means for extion chamber and in a position exposed to the movement ofthe whirlingair across the inner end of the plug during the suction and compression strokes, and a fuel injector located in said head for projecting finely divided liquid fuel during the latter portion of the compression stroke transversely of the cylinder into the portion of the combustion space formed bythe piston so that a substantial portion of said combustible fuel-air mixture is formed in said portion of the combustion space below the level of the inner end of the plug.

4. A low compression internal combustion engine of the explosion typehaving liquid fuel injection commencing substantially ahead of top dead center and spark ignition for igniting a combustiblegair-fuel mixture formed prior to ignition,including a cylinder, a cylinder head, a piston in said cylinder having a substantially continuous upwardly extending collar portion,

stroke, including a valve located above the piston 7 and opening toward the combustion chamber from the underside of said head, means for ex-' hausting combustion gases including a 'valve located above the, piston and opening toward the combustion chamber from the underside of said head, a spark plug located in the head and projectlng downwardly into said main combustion chamber to one side of a diameter .0! the cylinder and in a position exposed to the movement jection means having orifices for projecting durk transversely of the cylinder into'the portion of the combustion space formed by said piston. at

least one or said orifices being positioned sosthat the axial projection of the center line oi. the fuel jet formed thereby intersects the surface of ,said

piston during the period of fuel injection on the 7 same side of said diameter as that of the spark plug and below the level of the inner end of the 10 spark plug.

I 'KNUT qoms mas HESSELMAN.

TORBJORN vrx'ron mus-mom. 

